 
 
 
10.4.2  Combining terms of the same type
The combine command
joins subexpressions of various types.
- 
combine takes two arguments:
- 
expr, an expression.
- function, the name of a function or class of
functions. function can be one of exp, log,
ln, sin, cos, or trig.
 
- combine(expr,function) returns the
expression with subexpressions corresponding to the second argument
combined.
The combine command can duplicate the effect of other commands.
- 
combine(expr,ln) or
combine(expr,log) gives the same result
as lncollect(expr) (see
Section 10.3.5).
- combine(expr,trig) or
combine(expr,sin) or
combine(expr,cos)
gives the same result as tcollect(expr)
(see Section 10.2.4).
Examples
| combine(exp(x)*exp(y)+sin(x)*cos(x)+ln(x)+ln(y),exp) | 
| combine(exp(x)*exp(y)+sin(x)*cos(x)+ln(x)+ln(y),trig) | 
or:
| combine(exp(x)*exp(y)+sin(x)*cos(x)+ln(x)+ln(y),sin) | 
or:
| combine(exp(x)*exp(y)+sin(x)*cos(x)+ln(x)+ln(y),cos) | 
| combine(exp(x)*exp(y)+sin(x)*cos(x)+ln(x)+ln(y),ln) | 
or:
| combine(exp(x)*exp(y)+sin(x)*cos(x)+ln(x)+ln(y),log) | 
|  | | | cosx sinx+ex ey+ln | ⎛ ⎝
 | x y | ⎞ ⎠
 | 
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